A frequency of vertical synchronization signal (V-sync frequency) and a frequency of horizontal synchronization signal (H-sync frequency) (which can be collectively called frequencies of synchronization signal) of a display are key parameters of the display, the former equals to a refresh frequency and the latter relates to a resolution. To ensure that the above two frequencies synchronize with each other, the V-sync frequency and the H-sync frequency of the display are firstly detected, then they are compared with standard H-sync frequencies and standard V-sync frequencies respectively, so that a correct frequency of synchronization signal may be obtained, thereby the display may display images.
Currently, in the detection of the correct synchronization signal, a detection of the V-sync frequency and a detection of the H-sync frequency are usually performed at the same time. Specifically, the detection of the correct synchronization signal comprises: a first step, creating a standard synchronization signal table (including standard V-sync frequencies and standard H-sync frequencies) in a memory, wherein, in the standard synchronization signal table, the standard H-sync frequencies are associated with the standard V-sync frequencies and resolutions; a second step, detecting a V-sync frequency and a H-sync frequency of the display; a third step, comparing the detected frequencies with the standard frequencies of synchronization signal in the standard synchronization signal table one by one, and when both the V-sync frequency and the H-sync frequency satisfy an error range allowed by the standard V-sync frequencies and an error range allowed by the standard H-sync frequencies, respectively, then it is regarded that a correct frequency of synchronization signal is obtained, thus a resolution of the display may be obtained, and the detection is completed; however, if no correct frequency of synchronization signal is obtained from the table, then it indicates that there is something wrong with the synchronization of the display. With the above method for detecting the synchronization signal, the resolution of the display may be obtained according to the V-sync frequency and the H-sync frequency of the display, wherein the resolution may play a key role in setting parameters such as a refresh frequency for the display.
The inventor of the application find that there are at least following problems in the prior art: as the standard V-sync frequencies and the standard H-sync frequencies are created in the same table, so a large capacitance of the table is required and the arrangement of the frequencies is irregular and complicated, therefore, when the detected V-sync and H-sync frequencies of the display are compared with those in the table, the procedure is complicated and low in speed.